PROSPECTS FOR MULTI-TEV TWO-BEAM LINEAR COLLIDERS*

Recent work at CERN and SLAC has opened the possibility of the development of concrete designs for electron positron linear colliders that have a center of mass energy substantially above 1 TeV [1,2]. These designs are based on high gradient, normal conducting acceleration with the power provided by an auxiliary beam that is efficiently accelerated in a fully loaded, low frequency linac. This type of power source offers a flexibility to develop linear collider designs that have a wide range of parameters. In particular, the choice of frequency can be made without regard to the availability of high power RF sources, at least up to about 30 GHz. This paper explores possible linear collider designs taking into account limits on acceleration gradient and beambeam effects. The study shows that electron positron linear colliders have an energy reach far in excess of 1 TeV. In particular we show that an X-band linear collider powered with conventional sources might be upgraded using two-beam techniques to an energy far above 1 TeV. Thus, the linear collider offers a platform for continued exploration at the energy frontier of High Energy Physics.

Fully Coherent X-ray Pulses from a Regenerative Amplifier Free Electron Laser

We propose and analyze a novel regenerative amplifier free electron laser (FEL) to produce fully coherent x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought back to the beginning of the undulator to interact repeatedly with subsequent bunches in the bunch train. The FEL interaction with these short bunches not only amplifies the radiation intensity but also broadens its spectrum, allowing for effective transmission of the x-rays outside the crystal bandwidth. The spectral brightness of these x-ray pulses is about two to three orders of magnitude higher than that from a single-pass SASE FEL.Comment: 11 pages, 6 figure

Metal Distributions, Efficient n-Type Doping, and Evidence for in-Gap States in TiNiM_<i>y</i>Sn (M = Co, Ni, Cu) half-Heusler Nanocomposites

XNi1+ySn nanocomposites consisting of a XNiSn half-Heusler (HH) matrix with segregated XNi2Sn Full Heusler (FH) inclusions promise improvements in thermoelectric efficiencies. We extend recent research by reporting on TiNiMySn (0 ≤ y ≤ 1) nanocomposites with M = Co (3d9), Ni (3d10) and Cu (3d104s1). Neutron powder diffraction reveals that the Ni and Cu series produce a matrix of TiNiSn with nanosegregated TiNi2Sn and TiNi1+dCu1–dSn, respectively. For the Co series, the Co inserts into both phases to obtain a TiNi1–yCoySn matrix with nanosegregated TiNi2–yCoySn. Systematic changes in Seebeck coefficient (S) and electrical resistivity (ρ) are observed in all three series. For M = Ni, changes in S and ρ are attributed to in-gap states arising from the nanosegregation. The M = Co composites show a complex interplay between the hole doped TiNi1–yCoySn matrix and similar in-gap states, where the p- to n-type transition temperature increases but the maximum S remains unchanged at +30 μV K–1. The 4s1 electron for M = Cu is delocalized in the HH matrix, leading to metal-like ρ(T) and up to 100% improved thermoelectric power factors compared to TiNiSn (S2/ρ = 2 mW m–1 K–2 at 600–700 K for y = 0.025). These results broaden the range of segregated FH phases that could be used to enhance HH thermoelectric performance

Explicit Memory For Unattended Information

Explicit recognition memory of unattended information was tested in two studies. College students performed complex mental addition problems in the presence of distracting words, with instructions to concentrate on rapidly and accurately verifying the accompanying arithmetic answers. Then, they took a surprise recognition test on the words. Experiment 1 showed that a short exposure (800 msec) resulted in chance levels of recognition performance, whereas a longer exposure (1,100 msec) supported recognition barely better than chance. Experiment 2 addressed whether attended and unattended encoding are qualitatively different mental states or instead the same state, differing only in the degree of attention given. A state-dependent memory effect was observed, in which reactivating the same attentional state at the time of test as had occurred at the time of study had beneficial effects on recognition performance. This outcome adds to other types of evidence, which suggest that attended and unattended encoding differ qualitatively. It was concluded that unattended encoding supports an impoverished degree of explicit, as well as implicit, long-term memory. © 1989, Psychonomic Society, Inc.. All rights reserved

IS 501 Kingdom, Church, and World

(1) Clapp, Rodney. A Peculiar People: The Church as Culture in a Postchristian Society. Downers Grove, IL: IVP, 1996. (2) McLaren, Brian D. A New Kind of Christian. San Francisco: Jossey-Bass, 2001. (3) Snyder, Howard. Kingdom, Church, and World. Wipf and Stock, 2001. (4) Willimon, William. Shaped by the Bible. Grand Rapids: Eerdmans, 1990. (5) Wright, N.T. The Challenge of Jesus. Downers Grove, IL: InterVarsity, 1999.https://place.asburyseminary.edu/syllabi/2274/thumbnail.jp

IS 501 Kingdom, Church, and World

(1) Clapp, Rodney. Border Crossings. Brazos Press, 2000. (2) McClaren, Brian D. A New Kind of Christian. Jossey-Bass, 2001. (3) Newbiggen, Leslie. The Open Secret: An Introduction to the Theology of Mission. Grand Rapids, Michigan: Wm.B. Eerdmans, 1995. (4) Snyder, Howard. God’s Kingdom Now. Wiff and Stock, 2001. (5) Wright, Tom. The Challenge of Jesus. Downers Grove, Illinois: InterVarsity, 1999.https://place.asburyseminary.edu/syllabi/2275/thumbnail.jp

Effects of Osmolality and Ionic Strength on Secretion from Adrenal Chromaffin Cells Permeabilized with Digitonin

Hyperosmotic solutions inhibit exocytosis of catecholamine from adrenal chromaffin cells at a step after Ca 2+ entry into the cells. The possibility that the inhibition resulted from an inability of shrunken secretory granules to undergo exocytosis was investigated in cells with plasma membranes permeabilized by digitonin. The osmoticants and salts used in this study rapidly equilibrated across the plasma membrane and bathed the intracellular organelles. When sucrose was the osmoticant, secretion was not significantly inhibited unless the osmolality was raised above 1,000 mOs. When the osmolality was raised with the tetrasaccharide stachyose or a low-molecular-weight maltodextrin fraction (average size a tetrasaccharide), one-half maximal inhibition occurred at 900–1,000 mOs. Prior treatment of permeabilized cells with Ca 2+ in hyperosmotic solution did not result in enhanced secretion when cells were restored to normal osmolality. Increased concentrations of potassium glutamate or sodium isethionate were more potent than carbohydrate in inhibiting secretion. Half-maximal inhibition occurred at 600–700 mOs or when the ionic strength was approximately doubled. The inhibition by elevated potasium glutamate also occurred when the osmolality was kept constant with sucrose. Increasing the ionic strength did not alter the Ca 2+ sensitivity of the secretory response. Reducing the ionic strength by substituting sucrose for salt reduced the Ca 2+ concentration required for half-maximal stimulated secretion from approximately 1.2 Μ M . Chromaffin granules, the secretory granules, are known to shrink in hyperosmotic solution. The experiments indicate that shrunken chromaffin granules can undergo exocytosis and suggest that in intact cells elevated ionic strength rather than chromaffin granule shrinkage contributes to the inhibition of secretion by hyperosmotic solutions. The experiments place limits on the possible osmotic mechanisms that could be involved in exocytosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66041/1/j.1471-4159.1986.tb08502.x.pd

IS 501 Christian Formation: Kingdom, Church, and World

Donovan, Vincent. Christianity Rediscovered. Orbis Books, 2003. Hart, Trevor. Faith Thinking: The Dynamics of Christian Theology. Downers Grove, IL: IVP, 1995. Hauerwas, Stanley and William Willimon, Resident Aliens, Abingdon, 1989. McLaren, Brian D. The Story We Find Ourselves In. San Francisco: Jossey-Bass, 2003. Snyder, Howard. Kingdom, Church, and World. Wipf and Stock, 2001. Wesley Reading Packet available at Cokesburyhttps://place.asburyseminary.edu/syllabi/2517/thumbnail.jp

Plasma Membrane and Chromaffin Granule Characteristics in Digitonin-Treated Chromaffin Cells

Digitonin permeabilizes the plasma membranes of bovine chromaffin cells to Ca 2+ , ATP, and proteins and allows micromolar Ca 2+ in the medium to stimulate directly catecholamine secretion. In the present study the effects of digitonin (20 Μ M ) on the plasma membrane and on intracellular chromaffin granules were further characterized. Cells with surface membrane labeled with [ 3 H]galactosyl moieties retained label during incubation with digitonin. The inability of digitonin-treated cells to shrink in hyperosmotic solutions of various compositions indicated that tetrasaccharides and smaller molecules freely entered the cells. ATP stimulated [ 3 H]norepinephrine uptake into digitonin-treated chromaffin cells fivefold. The stimulated [ 3 H]norepinephrine uptake was inhibited by 1 Μ M reserpine, 30 m M NH 4 + , or 1 Μ M carbonyl cyanide p -trifluoromethoxyphenylhydrazone (FCCP). The data indicate that [ 3 H]norepinephrine was taken up into the intracellular storage granules by the ATP-induced H + electrochemical gradient across the granule membrane. Reduction of the medium osmolality from 310 mOs to 100 mOs was required to release approximately 50% of the catecholamine from chromaffin granules within digitonin-treated chromaffin cells which indicates a similar osmotic stability to that in intact cells. Chromaffin granules in vitro lost catecholamine when the digitonin concentration was 3 Μ M or greater. Catecholamine released into the medium by micromolar Ca 2+ from digitonin-treated chromaffin cells that had subsequently been washed free of digitonin could not be pelleted in the centrifuge and was not accompanied by release of membrane-bound dopamine-Β-hydroxylase. The studies demonstrate that 20 Μ M of digitonin caused profound changes in the chromaffin cell plasma membrane permeability but had little effect on intracellular chromaffin granule stability and function. It is likely that the intracellular chromaffin granules were not directly exposed to significant concentrations of digitonin. Furthermore, the data indicate that during catecholamine release induced by micromolar Ca 2+ , the granule membrane was retained by the cells and that catecholamine release did not result from release of intact granules into the extracellular medium.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65144/1/j.1471-4159.1985.tb07226.x.pd